1. Technical Field
The present invention relates to a polyphenylene sulfide resin composition suitable for injection molding.
2. Background Art
Polyphenylene sulfide (hereinafter called PPS) resins have excellent properties such as heat resistance, barrier properties, chemicals resistance, electric insulation and moist heat resistance suitable as engineering plastics, and are usually injection-molded for use as various electric and electronic parts, machine parts, automobile parts and so on.
However, PPS resins are lower in toughness than other engineering plastics such as nylon and PBT, being limited in applicable range, and the improvement of PPS resins is highly demanded.
For improving the toughness of PPS resins, methods of melt-blending various soft resins and the like have been studied. For example, U.S. Pat. No. 4,581,411 discloses adding a polyolefin-based elastomer such as ethylene/propylene copolymer elastomer to PPS, and U.S. Pat. No. 4,889,893 discloses a method of adding an α-olefin-glycidyl methacrylate copolymer, etc. However, these PPS resins do not have sufficient impact properties.
U.S. Pat. No. 5,625,002 discloses a method in which an olefin copolymer containing epoxy groups and an elastomer free from epoxy groups and acid anhydride groups are mixed with a specific PPS resin. JP2000-198923A discloses a method in which an ethylene/α-olefin copolymer having a specific molecular weight distribution and an olefin copolymer containing functional groups such as epoxy groups and acid anhydride groups are mixed with a PPS resin. Furthermore, JP2002-226706A discloses a method in which a specific olefin copolymer is finely dispersed into a specific PPS resin for achieving a high impact resistance of 700 J/m or more in Izod impact strength.
However, as PPS resin materials are being used in wider areas in recent years, the materials are required to have more sophisticated properties such as the moldability for allowing oversized parts to be molded and the toughness at low temperature. In this situation, the resin compositions proposed so far cannot sufficiently satisfy these requirements, and it is demanded to develop an economically advantageous material having higher flowability (moldability), impact properties and low-temperature toughness.